Serious problem ?

[gyroplanes]

I found this condition and would like some opinions on it. I'll try to word this as descriptivley as I can..

You have a heavy gyro with the requisite heavy, long rotor system.
When you move your joystick forward, off the rear stop, and set the massive rotorhead and rotorblades in motion and suddenly stop the stick, would you expect the inertia of the head/blades to bend the joystick?
Would you tolerate the flexing of the stick metal?
What do you think would eventually happen?

I don't know if the above scenario has ever happened to anyone.
But I found an even scarier one exists, in a large percentage of the fleet.

RAF & GBA gyroplanes have the "cross over" tube (the "tube" that connects the rotorhead torque tube to the pushrods) I quote "tube" because, unlike other gyros, the RAF & GBA use a solid aluminum bar, i believe they call it a gimble actuation arm.

The next time you go out to your RAF or GBA SH, move your joystick to neutral. Wait for the teetering to stabilize.

Now, with some vigor, pump the stick back and forth about 4 inches watching your torque (tube) bar.

The center of the bar and tips of the cross over bar will move in different directions. This movement, viewed from the front or back, will resemble a bird flapping it's wings.

I realize that we don't often pump our joysticks in flight, but every taxi out or exaggerated movement of the stick can cause a flex in the crossover and those flexations cause metal fatigue.

I believe it's just a matter of cycles before failure.

[Caribean_gyro]

In my twinstar is a hugh triangualr plate.
ChuckP

[Mark Sanders]

Originally Posted by gyroplanes

I found this condition and would like some opinions on it. I'll try to word this as descriptivley as I can..

You have a heavy gyro with the requisite heavy, long rotor system.
When you move your joystick forward, off the rear stop, and set the massive rotorhead and rotorblades in motion and suddenly stop the stick, would you expect the inertia of the head/blades to bend the joystick?
Would you tolerate the flexing of the stick metal?
What do you think would eventually happen?

I don't know if the above scenario has ever happened to anyone.
But I found an even scarier one exists, in a large percentage of the fleet.

RAF & GBA gyroplanes have the "cross over" tube (the "tube" that connects the rotorhead torque tube to the pushrods) I quote "tube" because, unlike other gyros, the RAF & GBA use a solid aluminum bar, i believe they call it a gimble actuation arm.

The next time you go out to your RAF or GBA SH, move your joystick to neutral. Wait for the teetering to stabilize.

Now, with some vigor, pump the stick back and forth about 4 inches watching your torque (tube) bar.

The center of the bar and tips of the cross over bar will move in different directions. This movement, viewed from the front or back, will resemble a bird flapping it's wings.

I realize that we don't often pump our joysticks in flight, but every taxi out or exaggerated movement of the stick can cause a flex in the crossover and those flexations cause metal fatigue.

I believe it's just a matter of cycles before failure.

My sparrow hawk has that set up and in flight every movment is very sudle and when I am making a full stop landing after the nose wheel touches the ground then the stick is brought full forward on the stop and the blades are still over 100mph and no sign of a problem so far and I have not herd of any yet. the rotor brake is not engaged until the blades are at or below 75 mph.

[gyroplanes]

I guess I'm not very good at getting my point across. I tried to elaborate on my concerns in the GBA thread above. I will consolidate my answers there instead of running two separate threads. (see GBA thread above)

[Steve Osborne]

Here is a photo of the part RAF updated a few years ago.

[gyroplanes]

I hope you all note the "?" in the thread title. I'm not an aeronautical engineer or metallurgist, but I do know, that if any part of my control system flexes, it WILL lead to fatigue failure at some point. "When" is the only unknown.

[LASsociety]

Many hombuilts (i speak of fixed wing experience) have people add things that they think will make the aircraft stronger and end up with a heavy, over-built aircraft. Gyrocopters are probably the exception for me. The extra weight of a triangular piece or reinforced brace wouldn't adversly affect anything, and would certainly help me sleep at night.

[tomhall]

Anyone know a source ( other than RAF in Africa ) for that new & improved torque tube ? Tom T. Hall in MN

[Steve Osborne]

Tom, how are the new blades working?

[tomhall]

Steve, Thanks for asking. I had only 3 flights with the new blades last Nov. before weather and darkness arrived. On each flight I had to apply significant back pressure on the stick to remain level. I thought my mast may have shifted, but it had not. Ther answer, from Ron Menzie, is quite simple: the Sportcopter blades are " cleaner " than the RAF blades, which offered more drag. I was trimmed to the RAF blades; I changed " wings " , the cleaner wing would by nature put me nose down a bit. Last week I switched from mast position # 3 to #4 ( more verticle ). I still have to apply some back stick to keep level. I would still like to level the gyro without a lot of trim spring pressure, but I may try 2 springs on each side ( not 1 stronger one ) in case 1 breaks. I was hoping I could simply put on the new blades and fly into the sunset; but everything is inter-dependent. It was suggested I make a new torque tube with the offset 1/8" closer together; that seems a bit dramatic. Anyone else with Sportcopter experience ? Thanks Tom

[LARRYEBOYER]

Tom. Does the gyro fly faster with the nose down? How you doing Man? Call me!!!

[CLS447]

Tom, I see that you got no response to the SC blade question.

I would do a forum search.....at least a few guys switched to the SC blades with great results.

Stan Foster, Tim O conner & others. Good Luck

[kss1000e]

Do you there is the size diagram paper? Thanks

[giro5]

Steve, post 6, the picture. Those lightning holes in the horizontal bar look too big ie, not enough metal left on the top and bottom of the bar. That bar is scary to me.

[earthbnd misfit]

Even the 4 x 6 mm bolts that hold on the piller posts seem weak. It doesn't take much to strip the threads.